NEW YORK — Billed as the single-largest archive of Pierre-Auguste Renoir's personal property, an upcoming auction of hundreds of personal letters, photos and other memorabilia offers a candid look inside the master painter's life as an artist, loving husband and devoted father.

The Renoir Estate Collection is set to be sold in New York on Sept. 19 as 143 lots. Heritage Auctions has estimated its value at $3 million.

In addition, the sale includes 19 original sculptural plaster models, or maquettes, created during Renoir's twilight years between 1913 and 1918 with the help of a young assistant, Richard Guino.

A consummate artist who painted every day of his life, Renoir died in 1919. His personal archive remained with his heirs until 2005, when his grandson Paul offered it for sale as a single lot at a Maryland auction at which it was purchased by the current owner.

“It is a gold mine,” said Virginie Journiac, an art historian and former curator of the Renoir Museum in Cagnes-sur-Mer, in the south of France. “These personal Renoir pieces will be seen for the last time as a unique collection unless a single buyer is able to purchase all the lots.”

Other objects in the sale include Renoir's polka-dotted silk scarf, marriage license and a notebook full of critic's reviews. There are letters from his contemporaries Claude Monet and Edouard Manet; his Legion of Honor medals; hundreds of glass-plate negatives; and documents relating to the construction of Les Collettes, his estate at Cagnes-sur-Mer.

Several museums, reached for comment, declined to say if they would bid.

The collection “illuminates the career, life and eminence of this very, very humble man,” said Brian Roughton, managing director of fine art at the auction company. “It shows the amount of his insecurity about his life, about being an artist ...”

Celebrated for his sensual nudes and charming landscapes, Renoir's sculptures are less known. The maquettes, many of which remained at Les Collettes until 1960, were based on Renoir's drawings and paintings and were produced after a crippling arthritis had nearly paralyzed his hands. Guino was paid to work under Renoir's guidance and did not sign the works.

A court recognized him as a co-author in 1973.

The current seller, who also owns the maquettes, got embroiled in a legal battle with the Guino family over the copyright of eight of the maquettes. The case was settled in 2008, and the auction house said all the material was being offered free and clear.

The auction house did not identify the consignor but published reports at the time identified her as Tracy Penwell, an Arizona gallery owner.

Renoir considered “Large Venus Victorious,” a life-size statue of the Roman goddess elegantly holding a drape in one hand and an apple in the other, a masterpiece. Created in 1914-1915, it is estimated to bring $900,000 to $1 million.

The auction also features the only two sculptures entirely executed by Renoir's hands — a medallion (est. $20,000) and bust of his youngest son Claude, “Coco” (est. $30,000).

“Woodcocks” (est. $80,000-$120,000) is the only painting in the sale. The small picture is of great historical significance because it is believed to be Renoir's last work, said Journiac, whose just-published book “The Late Renoir, The Riviera Years” is largely based on the material in the collection.

“He painted this still life with two dead birds some hours before he died, which is quite symbolic,” she said.